The electronics industry is currently shifting away from traditional parallel communication methodologies towards new, high-speed serial communication technologies. For instance, traditional parallel-based peripheral component interface (PCI) technologies are being supplanted by serial-based PCI Express technologies, which provide for faster communications. Similarly, parallel ATA (PATA) technologies employed for storage devices are being supplanted by serial ATA (SATA) technologies, which provide for faster communications.
A serial link is thus a link that allows a component, such as a peripheral or a storage device, to communicate serially with another component or a host computing device, where the host computing device has a corresponding serial link. A serial link includes a serial link transmitter to transmit data. A serial link also includes a serial link receiver to receive data.
An important aspect in developing a reliable serial link is to test its serial link receiver. Particularly, the serial link receiver has to be tested to ensure that it is capable of receiving data at the rated bandwidth of the serial link, among other constraints. Two conventional approaches to serial link receiver testing include employing an inverter and employing a multiplexer.
Employing an inverter to test a serial link receiver includes placing the inverter on an input of the serial link receiver to generate a test signal. However, this inverter-based approach is less than ideal, because it limits the termination voltage on the input to the pre-designed maximum termination voltage of the serial link receiver. As a result, a given serial link receiver cannot be tested past its already established tolerances.
Employing a multiplexer to test a serial link receiver includes placing an output of a multiplexer at some point of the data path within the serial link receiver associated with an input of the serial link receiver to generate a test signal. However, this multiplexer-based approach is also less than ideal, because multiplexers generally cannot be switched at the high bandwidths of serial link receivers. Furthermore, there can be limitations associated with positioning a multiplexer on a given serial link receiver.
For these and other reasons, therefore, there is a need for the present invention.